Buycoins allows you to trade cryptocurrencies with other users. Previously, this was facilitated by the now deprecated Peer-to-Peer platform but we've moved to using an order book.
An order book is a dynamic electronic list of buy and sell orders for an asset (in this case, cryptocurrencies) organized by price level.
Orders in an order book are separated into two sides: bids (buy orders) and asks (sell orders). Bids are the price a trader is willing to buy at and Asks are the price a trader is willing to sell at.